Resting Metabolic Rate (RMR) Test

A resting metabolic rate test measures how many calories your body burns at rest. You breathe normally into a mask or hood while a metabolic cart measures the oxygen you use, which converts into calories per day.

Your measured calories burned at rest per day, the number a prediction equation expects for someone your size, and your RER, which shows whether you burn mostly fat or carbohydrate at rest.

Book a morning appointment so the fast is easy. For 12 hours before, have nothing but water: no food, caffeine or alcohol. Wait at least 4 hours after nicotine, appetite suppressants or allergy medication, as they can affect your result. Skip moderate or vigorous exercise for 24 hours. Leave extra time so the trip in is calm, without brisk walking, running or lots of stairs. Wear comfortable clothes. Food, caffeine and exertion raise your burn for hours, which is why the rules are strict. Have breakfast and coffee straight after.

You breathe into the mask or hood for about 10 to 20 minutes. Allow 30 to 60 minutes for the whole visit.

Repeat tests under the same conditions usually agree within 2 to 4%. A change between two tests needs to be more than about 6 to 8%, roughly 100 to 135 calories a day, to be a real change rather than normal day-to-day variation.

BMR is the strict lab version, measured on waking after an overnight stay in a temperature-controlled room. RMR is the practical version and runs slightly higher, often by up to about 10%. Most calculators use the two terms interchangeably. Your total daily burn is RMR plus digestion and activity.

There's no single good number, because it depends on your size and muscle. What matters is how yours compares with a prediction for you. For a 45-year-old woman who is 165 cm and 75 kg, the standard formula predicts about 1,395 calories a day. A measured 1,256 to 1,535 is in line; a measured 1,200 would be about 86% of predicted.

No. Resting metabolism was once used to check the thyroid, but blood tests replaced it in the 1950s. Today thyroid function is checked with TSH and thyroid hormone blood tests. A low RMR can be a reason to check your labs, not a diagnosis.

Some DEXA reports list an RMR, but a DEXA scanner can't measure your breathing, so that figure is calculated from your lean mass. Lean mass explains about 63% of the differences in resting burn between people, so it beats a height and weight formula. It is still an estimate: about a quarter of the difference isn't explained by body composition. An RMR test measures it.

There's no official schedule. Most people test once for a baseline, then again after losing 5 to 10% of their body weight, or every 3 to 6 months during an active diet or GLP-1 course. Test at the same time of day with the same preparation each time.

University labs charge about $40 to $100, and commercial clinics usually $110 to $240. Your price is shown on this page, and members pay less. It includes booking and the report in your Mito dashboard, and it is the same whichever partner center you choose.

It is most useful when your calorie number matters: weight loss has stalled, you're on a GLP-1, you train hard, or you're in midlife and your body is changing. If your weight and habits are stable and working, a calculator may be close enough.

Every test shows the member price next to the standard non-member price, so you can see what membership saves you. The member price is our cost, covering the lab and what it takes to run the service. It is never a profit on the test itself. Mito makes its money on the membership, not on marking up your tests. Membership is $9 per month or $99 per year, and any applicable lab order or draw fee is itemized before you pay.

Yes. Mito's lab tests are HSA/FSA eligible, so you can pay with pre-tax dollars.

Add the test to your cart and select "Pay with HSA/FSA" at checkout. You'll finish on the secure checkout page of Flex, our HSA/FSA payments partner, and Flex emails you an itemized receipt from notifications@withflex.com for your records.

Most Mito tests are auto-substantiated, so you usually won't need a Letter of Medical Necessity. If your HSA/FSA administrator asks for more, contact us and we'll help.

You must be 18 or older to order a scan or fitness test through Mito. For most of them, you answer a few short health questions before you add one to your cart, so we can check that the test is right for you.

• Coronary Artery Calcium Scan: for people aged 40 to 75 with at least one heart risk factor and no known heart disease or heart symptoms. Risk factors include high cholesterol or blood pressure, diabetes, a family history of heart disease, a BMI over 25, smoking, or an inactive lifestyle. You'll also give your primary care provider's details.
• DEXA scans: not available if you're pregnant or may be pregnant, or if you've recently had a barium exam. If you have metal implants, a physician reviews your answers first.
• VO2 Max Test: not available if you're pregnant. Depending on your answers, you may need clearance from your own doctor before your appointment can be confirmed.
• Resting Metabolic Rate (RMR) Test: there are no health questions. You only accept the testing center's terms. It isn't recommended if you're pregnant or breastfeeding, and if you're ill, book once you've recovered.

If your answers mean a test isn't a good fit, you'll see why before you buy.

No. If your test needs a physician's order, it's arranged for you as part of booking. You don't need to contact your own doctor or bring an order with you.

The one exception is the VO2 Max Test. If your health questionnaire shows you need medical clearance, we'll ask your own doctor to sign off first.

After you buy your scan or fitness test, open your Mito dashboard and:

1. Answer the testing center's health questions for your test, if it has any. Some tests also ask for an emergency contact or your primary care doctor's details.
2. Enter your ZIP code to find the nearest testing center.
3. Pick two appointment times: your preferred time and a backup.

The center then confirms one of those times, usually within hours. We'll email you at each step: when we receive your booking request, when the center confirms your appointment, and a reminder before your visit. If your appointment is cancelled or missed, we'll let you know by email too.

Requested means we've sent your preferred times to the testing center, but the appointment isn't final yet. It may still be waiting on the center, on your health questions, or on a doctor's clearance.

Confirmed means the center has finalized your appointment and expects you at the date and time in your confirmation email.

Please don't treat a requested appointment as final. If it hasn't been confirmed within 48 hours, message Mito Concierge or email help@mitohealth.com.

You can reschedule or cancel from your Mito dashboard.

• Rescheduling: your first two reschedules are free when you make them more than 24 hours before your confirmed appointment. Each reschedule after that costs $25. If the center changes your time, that doesn't count toward your free reschedules.
• Cancelling more than 24 hours ahead: your purchase stays open while our care team reviews whether to refund it or use it to rebook. Refunds aren't automatic, so message us if you have a preference.
• Cancelling 24 hours or less before your appointment, or missing it: your purchase is forfeited. A new appointment needs a new purchase at the full price.

Follow the instructions in your confirmation email, because they can affect your results. If you don't prepare as instructed, the center may not be able to do the test.

For every appointment

• Bring a photo ID and your confirmation or reminder email.
• Arrive about 5 minutes before your appointment. Many centers have little waiting space, so don't arrive much earlier. If you're late, the center may not be able to see you.
• Don't bring children, and avoid bringing guests.

DEXA scans

• Wear comfortable clothes, such as gym clothes, with no metal or hard plastic. That means no zippers, buttons, underwire, jewelry, or watches.
• Don't eat for 2 to 4 hours before. Drink water normally.
• Avoid intense exercise, saunas, and steam rooms for 12 hours before.
• Tell the staff if you have metal in your body, such as a pin or a joint replacement.

VO2 Max Test

• Don't exercise for 24 hours before.
• Be well hydrated and fed, but avoid a heavy meal in the 2 to 3 hours before. A light snack is fine.
• Wear the clothes and shoes you normally exercise in.
• Allow 1 to 1.5 hours.

Coronary Artery Calcium Scan

• No alcohol or caffeine for 4 hours before.
• No strenuous exercise for 24 hours before.
• Wear clothes that are easy to take off, with no metal. A gown may be provided.

Resting Metabolic Rate (RMR) Test

• Book a morning appointment, so most of the fast happens while you sleep.
• Have nothing but water for 12 hours before: no food, caffeine, or alcohol.
• Wait at least 4 hours after nicotine, appetite suppressants, or allergy medication.
• No moderate or vigorous exercise for 24 hours before.
• Leave extra time so the trip in is calm, without brisk walking, running, or lots of stairs.

Your results are uploaded to your Mito dashboard, where you can view and download them. They usually arrive within 24 hours of your appointment, and officially within 2 business days. If you haven't seen them after 5 business days, message Mito Concierge or email help@mitohealth.com and we'll check.

Yes. Consultations are available to review your results and talk through what they mean for you. You can book one from your Mito dashboard.

Available in all 50 states and Washington, DC.